[The properties of visual functions and familial analysis in blue cone monochromatism]

The diagnosis of blue cone monochromatism (BCM) is based on severely affected color vision with preserved blue function, nearly absent photopic ERG, and a family pedigree compatible with X-linked inheritance. In the past, there has been no familial report of BCM in Japan. We found a Japanese family with BCM and studied the ocular findings of three affected members and a female carrier. Two of three affected members showed unique properties of BCM in their visual functions, including color vision and ERG. One affected member, a brother of their mother (43 years old), showed achromatic color vision. He had diabetic retinopathy and moderate cataract, which, might have disturbed his preserved blue cone function, resulting in the achromatic vision. A female carrier showed normal visual function, except that her photopic ERG was slightly reduced in amplitude.